The present invention relates to a method and apparatus for selecting safety parameters to be monitored as a finction of the configuration of a machine-tool.
It is generally known, when working with machine-tools, to isolate the working area from its immediate surroundings by using protective doors or gates. The purpose of this is to prevent injury to the machine operator in the event of a dangerous operating condition (tool breakage, improper tool or workpiece motion, or the like). To ensure that this protective measure cannot be by-passed, the protective doors are monitored and, in response to opening of the protective doors, axles of the machine-tool are shut down or their travel path is restricted. In addition, to improve operational safety, the actual positions of the axles of a machine-tool are monitored. This enables one to recognize and prevent any travel along the axes into an unauthorized area. In this context, to perform the monitoring operation and activate the safety-related measures, a special monitoring program is used, in which the detectors to be monitored for each individual configuration are defined.
This monitoring method has the drawback of not being flexible enough and not being adaptable to various machine-tool configurations. When the monitoring operation is implemented in a program, one must revise the entire program if one detail of the monitoring system, for example one safety parameter or one detector, is changed. In addition, monitoring programs of this kind turn out to be increasingly complicated due to the ever greater number of increasingly detailed machine-tool operating states to be monitored. Such systems are therefore, neither easily serviced nor easily modified.
Therefore, the object of the present invention is to provide a method and apparatus for implementing the procedure, which will make it possible to avoid the above-mentioned disadvantages. It is the aim of the present invention to devise a flexible plan for storing and selecting safety parameters as a function of a machine-tool configuration.
The method according to the present invention advantageously provides a memory for storing the safety parameters to be monitored for every conceivable machine-tool configuration, for example, the door switches of the protective doors, or the lines which carry the signals from the door switches to be monitored, and/or the coordinates of the protected zones to be monitored, or the lines used to transmit the coordinates to be monitored. On the basis of the data specifying the special machine-tool configuration, a memory is addressed, and from a table stored therein, the safety parameters to be monitored, such as door switches for the protective doors in question, and the minimum and maximum actual positions, are read out for each axel. Since the monitoring program according to the present invention utilizes these safety parameters that are read out from the memory, it can have a universal design, making it independent of any special machine-tool configuration. Therefore, the data for all possible machine-tool configurations required for a monitoring operation are centrally stored in one memory. At fixed intervals, a processor checks whether all signals of doors"" switches output from the memory signal indicate closed protective doors, and whether the actual axel positions are located within the protected zone. Therefore, it is no longer necessary to constantly monitor all door switches and actual axel positions, but rather only those relevant to a safe operating condition of the machine-tool in the special configuration. If a monitored protective door is detected to be open, or if an axel position is outside of the protected zone, an error recovery routine is initiated. Steps are taken in performing this error recovery routine to re-establish a safe operating condition, for example, an axel recognized as defective is shut down, and a status message to this effect is output to the user.